Another install question

[selfguided]

First i would like to say i have been lurking for a long time while searching for a new vehicle. I decided on a 2003 Pathfinder LE 4X4. Liking it alot so far. I previously owned a 2003 Focus SVT, and was a member of FocalJet and FocusFanatics. I have found lots of useful information so far, think im gonna like it here.

I installed a new deck and am having some problems. I used the Metra 70-7551 harness kit to hook up the deck to the factory Bose speakers. I plan on hard-wiring everything once i get my replacement speakers, but for now, i wanted a quick install.

I am not getting any sound from my rear speakers. Also, i have to crank the volume near max to get the front speakers loud. The sub volume is all the way down to compensate for this. It is definitely hooked up correctly. I have checked the fuses for the factory Bose amps, they are fine. Any thoughts?

[alexf20c]

the universal harness you used does not have provisions to power bose amps, which are usually built into the speaker. you need to hot-wire the rear amp to ignition voltage.

compare your head unit harness to the original bose head unit harness, and you'll see the extra wires - usually orange. just run a jumper wire to another circuit that has ignition voltage (i.e. is only live when the key is ON)

[selfguided]

that harness does have amp-power leads. i know it sends power to the (front)amps, they are functional but just very quite. the blue/white stripe wire (amp power lead) and the black/white stripe (amp ground) are both connected. i think i just may have a toasted amp (the previous owner had an aftermarket deck hooked up with a different harness that sent speaker-level power to the amps). i have gone through everything i can imagine troubleshooting this. i think i am going to pull the cover in the rear and meter the amp. see if its getting power at the harness when the deck is on and go from there. thanks for the input though!
Modified by selfguided at 5:02 PM 12/12/2009

[ganesh21]

Check that the rear amp come on. It is located on the left in the rear hatch.

If you plan on changing the deck - it is always best to change everything.

[mda185]

I installed a new deck and am having some problems. I used the Metra 70-7551 harness kit to hook up the deck to the factory Bose speakers. I plan on hard-wiring everything once i get my replacement speakers, but for now, i wanted a quick install.

I am not getting any sound from my rear speakers. Also, i have to crank the volume near max to get the front speakers loud. The sub volume is all the way down to compensate for this. It is definitely hooked up correctly. I have checked the fuses for the factory Bose amps, they are fine. Any thoughts?

Before I installed my aftermarket amps, I used an Alpine head unit to drive the Bose amps. IIRC that is the same Metra harness I used to install my Alpine head unit. It has RCA plugs to connect the preamp outputs to the Bose amp input lines if it is the same one I used. This harness adapter sends the turn on signal to the amps if you wired it correctly.

The reason the sound must be cranked to even get moderately loud is the the Bose amps need a higher voltage drive signal. I have a post on this subject on this forum. Basically, you need to install a preamp/line driver like I did or use the speaker level outputs. Preamp outputs below 4 volts RMS will not drive the Bose amps correctly. Even 4 volts is marginal.

If your head unit has a common ground output where left and right channel - signals are tied to the head unit ground, you will not be able to drive the Bose amps with speaker level outputs. They have to be floating ground outputs or you will probably have alternator noise.

Modified by mda185 at 11:47 AM 12/22/2009
Modified by mda185 at 11:49 AM 12/22/2009

[selfguided]

i metered everything and the amp is fine. the pre-out voltage on this receiver is 6 volts, but still not strong enough a signal.

i installed a different head unit, everything is working perfectly. i assume the head unit's preamp was faulty.

thanks for the input on this, i am going to get a line driver to boost the signal of the new receivers outputs (5 volts). i dont like the idea of driving the amps with speaker-level signals. too much distortion.